Modelos matemáticos para estimativa da geometria do volume de bulbo molhado por irrigação por gotejamento superficial no agropolo Assu-Mossoró.

Abstract

Information on the geometry of wetted soil volume under trickle irrigation is important for the design and operation of these irrigation systems, and also for the management of irrigation as a function of emitter discharge and wetted volume. This research was carried out in the state of Rio Grande do Norte, Brazil, to study the effect of different combinations of emitter discharge and time of water application on the dimension and volume of wetting in six soils (Entisol, Ultisol, Inceptisol, Psamment, Oxisol, Fluvent). The factors time of water application (t = 1, 2, 4 and 7 h) and discharge rate (q = 1, 2, 4 and 8 L h-1) were studied in a split split-plot design with three replications. Trenches were open after application of the different water volumes and the following measures were taken: depth (Zmax), diameter at soil surface (Ds), maximum width (Dmax), and depth of maximum width (ZDmax). Models proposed were evaluated by Mean Squared Deviation (MSD) between predicted and measured values. Empiric equations for Dmax (q, t), Zmax (q, t), Ds (q, t) and ZDmax (q, t) adjusted well to power and surface response models. Values of the semi-empiric models proposed for maximum width had good agreement with field observed values. Models proposed also predicted wetted soil volume.